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If log (x5 y2) = 5a + 2b and log (x2 y5) = 2a + 5b, find log (xy) in terms of a and b?
log (x5 y2) = 5a + 2b
⇒ 5 logx + 2logy = 5a + 2b → (1)
Similarly, log (x2 y5) = 2a + 5b
⇒ 2 log x+ 5 log y = 2a + 5b → (2)
∴ log (xy) = log x + log y
Adding (1) and (2) 7 log x + 7 log y = 7a + 7b
log x + log y = a + b
fraction numerator 1 over denominator log subscript 2 straight x end fraction plus fraction numerator 1 over denominator log subscript 2 straight x end fraction plus fraction numerator 1 over denominator log subscript 4 straight x end fraction plus fraction numerator 1 over denominator log subscript 5 straight x end fraction plus fraction numerator 1 over denominator log subscript 6 straight x end fraction plus fraction numerator 1 over denominator log subscript 7 straight x end fraction
Similarly,
∴
=
= = logx 5040
If logx 4 = 0.4, then the value of x is:
logx 4 = 0.4 ⇔ logx 4 = ⇔x2/5 = 4 ⇔ x = 45/2 = (22)5/2
⇔ x = = 25 ⇔ x = 32.
The value of log2 [log2 log2 log2 (65536)] is
log2 log2 log2 log2 216 = log2 log2 log2 (16)
= log2 log2 log2 (24) = log2 log2 (4)
= log2 log2 (22) = log2 (2) = 1
If the logarithm of 19683 to a base is 6, then what is the base?
Let the base be x
Logx 19683 = 6 ⇒ x6 = 19683 = (3)6
∴ x = 3
If 5 + log10x = 5log10y, then express x in terms of y.
5 + log10x = 5 log10y
5 log1010 + log10x = log10y5 ⇒ log10x = log10y5 – log10105
⇒ log10x = log10 ⇒ x = y5/105 = (y/10)5
The value of log5 is:
Let log5 = n. Then, 5n = ⇒5n = 5–3 ⇒ n = – 3.
∴ log5 = –3.
Find the logarithm of 1728 to the base 2 square root of 3 .
let 1728 = x ⇒ (2)x = 1728
∵ 1728 = 26 ()6 = (2)6
(2)x = (2)6
On comparing ⇒ x = 6.
Find the logarithm of 64 × cube root of 512 to the base cube root of 8
= (3) (3) log88 = 9(1) = 9
Simplify: log2 log2 log2 log subscript square root of 3 end subscript 6561.
6151 = = 16
log2 16 = log224 = 4
log24 = log222 = 2
log22 = 1
∴ log2 log2 log2 log2 6561 = 1.
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